Actually, it's pretty well known how it can happen. It's fairly easy for people to rationalize not publishing a null result not favorable to their funding sour

Actually, it's pretty well known how it can happen. It's fairly easy for people to rationalize not publishing a null result not favorable to their funding source when null results are often not published anyway. [1] However, in aggregate, this means that studies that show unfavorable results to a funder are less likely to see publication. [1] http://en.wikipedia.org/wiki/Publication_bias http://en.wikipedia.org/wiki/Publication_bias